Stanley Forman Reed,
United States v. E. I. Du Pont De Nemours and Company…
“ The 'market' which one must study to determine when a producer has monopoly power will vary with the part of commerce under consideration. The tests are constant. That market is composed of products that have reasonable interchangeability for the purposes for which they are produced-price, use and qualities considered. While the application of the tests remains uncertain, it seems to us that du Pont should not be found to monopolize cellophane when that product has the competition and interchangeability with other wrappings that this record shows. ”
